Taenia saginata

• Taenia saginata

  Beef tape worm

  
• Definitive host

  • Humans
• Humans are never an intermediate host
• Ingestion of embryonated larva does not cause human cysticercosis

  
• Intermediate host

  • Cow
• Diagnostic stage

  • Egg
• Infective stage

  • Cysticercus bovis
• Habitat

  • Upper jejunum
• Autoinfection: NO
• Adult

  • Derives nourishment from the host
  • 4 - 10 meters
  • 1,000 to 4,000 proglottids
  • Unarmed (no rostellum and hooklets)
  • With 4 suckers
• Mature proglottid

  • TWO large ovaries
  • Median club-shaped uterus
  • Follicular testes
  • Lateral genital pores which receives the semen and transferred to the vagina
  • With vaginal sphincter
• Gravid proglottid

  • 15 - 20 lateral uterine branches
  • 97,000 to 124,000 ova
  • Motile

  
• Gravid proglottid of T. saginata

  • Can go out of anus
  • Can cause appendicitis, bile duct obstruction, and UTI among women
• Motile gravid proglottid of T. saginata

  • Can cause obstructive jaundice secondary to bile duct obstruction
  • Can cause vaginitis
  • Can cause urinary tract infection secondary to migrating T. saginata erratic infection

  
• Proglottids of Taenia are longer than they are wide
• Ova

  • Spherical, yellow to brown in color with thick radially striated embryonic shell
  • Oncosphere with 3 pairs of hooklets: hexacanth
  • Striations at the side of the shell
  • Not distinguishable from that of T. solium

  
• Cysticercus bovis

  • Presence of fluid-filled spaces called bladders
• Life cycle of Taenia saginata

  1. Humans eat undercooked meat infected with cysticerci

  2. Larva establishes itself in the small intestine and matures into adult

  3. Gravid proglottids release eggs passed to the fecal material

  4. Eggs ingested by intermediate host become oncospheres which encyst (cysticercus bovis) in the muscles

  5. Humans ingesting embryonated egg not infected, no cysticercosis

  6. Humans ingesting undercooked or raw pig meat infected with cysticerci, cysticerci matures into adult hermaphroditic Taenia saginata tapeworm

  
• Pathogenesis and Clinical Manifestations

  • One adult worm per patient
  • Worm is irritated by alcohol, sometimes proglottids are passed after bouts of alcohol drinking
  • Most common chief complaint: Passage of proglottid with no associated symptoms
  • Mild irritation at the site of attachment
  • Epigastric pain, vague discomfort, hunger pangs, weakness, weight loss, loss of appetite, pruritus ani
  • Proglottids are highly motile → obstruction in the bile and pancreatic duct and appendix
• Taenia asiatica

  Asian taenia
• First reported in Taiwan in 1980
• Endemic areas of Taenia asiatica

  • Korea
  • China
  • Philippines
  • Thailand
  • Malaysia
  • Indonesia
• Cysticerci of asiatica develop in the liver and other viscera of pigs and NOT in the muscle
• Does NOT produce cysticercosis in humans
• Morpholifcally and genetically similar to T. saginata
• Intermediate hosts

  • Goats
  • Monkey
  • Wild boar
  • Swine
  • Cattle
• Definitive host

  • Humans
• Diagnosis (saginata)

  • Identification of proglottids, eggs, scolex
  • Injection of India ink through genital pore → help in accurate counting of lateral branches of uterus
• Treatment (saginata)

  • Praziquantel as single does
  • Criteria for cure: recovery of scolex and negative stool examination 3 months after treatment